1. Field of the Invention
The present invention relates to an on-vehicle apparatus, a vehicle locking/unlocking system, and a method of controlling on-vehicle apparatus.
2. Description of the Related Art
In the related art, a vehicle locking/unlocking system where locking and unlocking of doors of a vehicle is implemented through wireless communications between an on-vehicle apparatus included in the vehicle and a portable apparatus that a user can have with him or her is known (for example, see Japanese Laid-Open Patent Application No. 2001-115699). Japanese Laid-Open Patent Application No. 2001-115699 discloses, as a portable apparatus, a remote unit that includes a battery, a first control circuit, and a transponder, and discloses, as an on-vehicle apparatus, a vehicle-side unit that includes a second control circuit.
The remote unit has the first control circuit for determining whether the battery is exhausted. The first control circuit returns an ID code (an identification code of the remote unit) of an RF signal in response to reception of electric waves for starting transmitted from the vehicle-side unit when the battery is not exhausted. On the other hand, the transponder returns a transponder ID code (an identification code of the remote unit) in response to having power supplied through electromagnetic induction caused by electric waves for starting transmitted from the vehicle-side unit when the first control circuit determines that the battery is exhausted. The second control circuit of the vehicle-side unit locks or unlocks doors of a vehicle based on a verification result on the ID code of the RF signal or the transponder ID code.